/**
 * @param {number} start
 * @param {number} goal
 * @return {number}
 */
 var minBitFlips = function(start, goal) {
  let a = start.toString(2)
  let b = goal.toString(2)
  const len = Math.max(a.length, b.length)
  a = a.padStart(len, '0')
  b = b.padStart(len, '0')
  let cnt = 0
  for(let i = 0; i<len; i++) {
    if(a[i] !== b[i]) cnt++
  }
  return cnt
};